Preparation method of fine-grain high-purity aluminum-silicon-copper alloy target blank for sputtering
阅读说明：本技术 一种溅射用细晶高纯铝硅铜合金靶材坯料的制备方法 (Preparation method of fine-grain high-purity aluminum-silicon-copper alloy target blank for sputtering ) 是由 马小红 徐亚军 元鹏超 白毅 张博 刘江滨 马青 于 2020-06-11 设计创作，主要内容包括：本发明为一种溅射用细晶高纯铝硅铜合金靶材坯料的制备方法。一种溅射用细晶高纯铝硅铜合金靶材坯料的制备方法,包括：S10配制中间合金：所述的中间合金为铝铜中间合金和铝硅中间合金；S20：将所述的中间合金与99.9995％纯度的高纯铝在真空熔炼炉中熔融,完全熔融后,得合金液；所述的合金液中硅含量为0.9-1.1wt％,铜含量为0.45-0.55wt％；S30：将所述的合金液采用高纯氩气进行在线精炼；S40：将经过在线精炼的合金液进行双极过滤；S50：将经过双级过滤的合金液进行φ120-164mm棒材坯料铸造,得所述的溅射用细晶高纯铝硅铜合金靶材坯料。本发明所述的一种溅射用细晶高纯铝硅铜合金靶材坯料的制备方法,制备的溅射用高纯AL-1wt％Si-0.5wt％Cu靶材坯料中微量杂质元素含量极低,溅射成膜性能好,且成分均匀。(The invention relates to a preparation method of a fine-grain high-purity aluminum-silicon-copper alloy target blank for sputtering. A preparation method of a fine-grain high-purity aluminum-silicon-copper alloy target blank for sputtering comprises the following steps: s10 preparing a master alloy: the intermediate alloy is an aluminum-copper intermediate alloy and an aluminum-silicon intermediate alloy; s20: melting the intermediate alloy and high-purity aluminum with the purity of 99.9995% in a vacuum melting furnace, and obtaining alloy liquid after complete melting; the alloy liquid contains 0.9-1.1 wt% of silicon and 0.45-0.55 wt% of copper; s30: carrying out on-line refining on the alloy liquid by adopting high-purity argon; s40: carrying out bipolar filtration on the alloy liquid subjected to online refining; s50: and casting the alloy liquid subjected to the two-stage filtration on a phi 120-164mm bar blank to obtain the fine-grained high-purity aluminum-silicon-copper alloy target blank for sputtering. According to the preparation method of the fine-grain high-purity aluminum-silicon-copper alloy target blank for sputtering, the prepared high-purity Al-1 wt% Si-0.5 wt% Cu target blank for sputtering has extremely low trace impurity element content, good sputtering film-forming performance and uniform components.)
1. The preparation method of the fine-grain high-purity aluminum-silicon-copper alloy target blank for sputtering is characterized by comprising the following steps of:
s10 preparing a master alloy: the intermediate alloy is an aluminum-copper intermediate alloy and an aluminum-silicon intermediate alloy;
preparing an aluminum-silicon intermediate alloy: melting high-purity aluminum with the purity of 99.9995 percent and high-purity silicon with the purity of not less than 99.999 percent in a vacuum melting furnace, controlling the melting temperature at 800-850 ℃, completely melting, stirring, and casting into a re-melted ingot to obtain the aluminum-silicon intermediate alloy: the content of silicon element in the aluminum-silicon intermediate alloy is 7-13 wt%;
preparing an aluminum-copper intermediate alloy: melting high-purity aluminum with the purity of 99.9995 percent and high-purity copper with the purity of not less than 99.999 percent in a vacuum melting furnace, controlling the melting temperature at 800-850 ℃, completely melting, stirring, and casting into a re-melted ingot to obtain the aluminum-copper intermediate alloy: the content of copper element in the aluminum-copper intermediate alloy is 20-25 wt%;
s20: melting the intermediate alloy and high-purity aluminum with the purity of 99.9995 percent in a vacuum melting furnace, controlling the melting temperature to be 730-745 ℃, and obtaining alloy liquid after complete melting; the alloy liquid contains 0.9-1.1 wt% of silicon and 0.45-0.55 wt% of copper;
s30: carrying out on-line refining on the alloy liquid by adopting high-purity argon;
s40: carrying out bipolar filtration on the alloy liquid subjected to online refining;
s50: and casting the alloy liquid subjected to the two-stage filtration on a phi 120-164mm bar blank to obtain the fine-grained high-purity aluminum-silicon-copper alloy target blank for sputtering.
2. The production method according to claim 1,
in the preparation method, the content of alumina in the lining material of the part contacting with the molten aluminum in the casting production line is required to be higher than 90 wt%.
3. The production method according to claim 1,
in the step S10: in the preparation of the aluminum-silicon intermediate alloy: stirring the aluminum liquid for 15min by using a graphite rotor after complete melting;
in the preparation of the aluminum-copper intermediate alloy: and stirring the aluminum liquid for 15min by using a graphite rotor after complete melting.
4. The production method according to claim 1,
in the step S10: before casting into a re-melted ingot, detecting the components of the intermediate alloy in the intermediate alloy liquid, detecting and preparing the components of the intermediate alloy of aluminum silicon and aluminum copper by using a glow discharge mass spectrometer, and controlling the total content of metal element impurities in the intermediate alloy to be less than 5 ppm.
5. The production method according to claim 1,
in the step S20, the master alloy is added twice, and the first addition amount is 80 wt% of the total addition amount.
6. The production method according to claim 1,
in the step S30, the flow rate of argon gas is 2-5m3H, 20min of refining time, and 740 ℃ of refining temperature 730-.
7. The production method according to claim 1,
in S40, two filter plates are adopted for on-line filtration; wherein the first stage filtration adopts a domestic 50PPI filter plate, and the second stage filtration adopts an imported 50PPI filter plate or a domestic 70PPI filter plate.
8. The production method according to claim 1,
in S50, a semi-continuous casting machine is used for water cooling to perform phi 120-3/h。
9. The method according to claim 8,
in the step S50, a smooth aluminum alloy crystallizer mould is adopted for casting.
Technical Field
The invention belongs to the technical field of sputtering targets, and particularly relates to a preparation method of a fine-grain high-purity aluminum-silicon-copper alloy target blank for sputtering.
Background
The rapid development and increased integration of semiconductor Integrated Circuits (ICs) have further increased the quality requirements for metal interconnect lines. The ultra-pure aluminum alloy target is used as a main matching material of a metal interconnection line in IC manufacturing, and the market scale of the ultra-pure aluminum alloy target is gradually enlarged. The quality of the sputtering target plays a crucial role in the performance of the metal thin film material.
Because the aluminum-silicon-copper film contains a small amount of silicon and metal copper, the sputtered film greatly reduces the metal aluminum puncture, so the aluminum-silicon-copper film is widely applied as a sputtering target material.
The high-purity aluminum sputtering target has high requirements on components, and mainly because alkali metal elements such as Na, K and the like can diffuse to PN junctions to cause the thin film to be penetrated; fe. Interface level leakage resistance is easily generated by heavy metal elements such as Ni; gas impurity C, O, N impairs the stability of the membrane; u, Th, etc., may induce miswork. Therefore, the finer the circuit structure is, the higher the purity requirement for the aluminum substrate and the high purity aluminum-based alloy is.
The high purity of the sputtering target material is required, and the preparation process of the alloy blank does not allow the addition of a grain refiner (such as AL-Ti-C/AL-Ti-B), so that the feather crystal defect (such as the central feather crystal defect shown in figure 2) is easily formed in the casting process of the high-purity aluminum-based alloy, and higher requirements are provided for the control of the casting process.
The prior patent CN109338313A (an aluminum alloy target and a preparation method thereof): the invention provides a preparation method of an aluminum alloy target, which takes copper, silicon and rare earth elements in corresponding atomic percentage as raw materials to prepare the aluminum alloy target, and improves the conductivity, corrosion resistance and oxidation resistance of the aluminum alloy target. Specifically, the addition of copper improves the conductivity of the aluminum alloy target, and the addition of silicon changes the thermal expansion coefficient of the aluminum alloy target and eliminates the compressive residual stress generated in the film, thereby eliminating the phenomenon of film-coating and improving the surface quality of the sputtering coating film. According to the preparation method of the aluminum alloy target material, all copper, silicon, rare earth elements and part of aluminum are mixed and melted to prepare the master alloy, the copper, the silicon and the rare earth elements are better melted and mixed with the aluminum in the preparation process of the master alloy, and then the melted and mixed aluminum-silicon-copper-rare earth alloy and the rest part of aluminum are melted and cast to form the ingot, so that the problems that the silicon and the copper are difficult to melt and the components are uniform are solved, and the aluminum alloy target material with uniform components is obtained. However, this patent describes the use of vacuum casting, but the casting process is not specified. For the control of the structure of the high-purity aluminum-based alloy, casting process parameters are key control points.
The prior patent CN110564983A (an aluminum-silicon-copper series cast aluminum alloy and a production method thereof): the invention discloses an aluminum-silicon-copper cast aluminum alloy and a production method thereof, wherein the aluminum-silicon-copper cast aluminum alloy is produced by using cast aluminum waste and deformed aluminum waste as raw materials; the production method comprises the following steps: sorting materials, preparing and distributing materials, melting in a primary furnace, alloying, adjusting components, refining, degassing on line, standing, casting, inspecting finished products and warehousing the finished products. The invention utilizes the cast aluminum waste and the deformed aluminum waste as the raw materials to produce the aluminum-silicon-copper cast aluminum alloy, has wide raw material sources, effectively solves the problem that a large amount of electric energy is consumed in electrolysis, and greatly reduces the production cost. Meanwhile, a large amount of cast aluminum waste and deformed aluminum waste in the market are effectively digested, secondary or repeated utilization of the waste is realized, the consumption of resources and energy sources is reduced, and higher economic benefits can be created; and the quality of the cast aluminum waste and the deformed aluminum waste is superior to that of the waste aluminum slices, so that the product quality of the aluminum-silicon-copper cast aluminum alloy can be greatly improved, and the aluminum-silicon-copper cast aluminum alloy has wide market prospect. However, the invention mainly uses cast aluminum and deformed aluminum waste materials for smelting and casting, the purity of the raw materials is far lower than that of the raw materials used in the invention, so the control method of the casting process is different, and the product purity cannot be ensured by using the technology of the invention.
The invention discloses a preparation method of a rare earth coating composite aluminum-silicon-copper alloy, which belongs to the prior patent CN108342622A (a preparation method of a rare earth coating composite aluminum-silicon-copper alloy). The invention improves the pinhole degree of the alloy by adjusting the process and parameter solution; the invention adopts a magnetron sputtering method and a low-temperature rolling method to form the rare earth memory alloy layer on the surface of the aluminum-silicon-copper alloy, so that the yield strength of the alloy can be improved, and the aluminum-silicon-copper alloy has uniform and compact surface, high film-substrate bonding strength and excellent mechanical property. However, the invention adopts the smelting and jet deposition technology to prepare an ingot blank, then uses the smelting method to prepare the rare earth memory alloy target material, and finally uses the magnetron sputtering method to form the film. The method does not relate to casting related process flow and casting parameters.
The invention discloses a preparation method and application of an aluminum-silicon-copper rare earth alloy material for metal mold casting, and relates to the prior patent CN103725935B (an aluminum-silicon-copper rare earth alloy material for metal mold casting and a preparation method and application thereof). The invention has the advantages that the automobile double-balance shaft shell cast by the aluminum-silicon-copper-rare earth alloy material can reduce the weight of two thirds of the existing automobile double-balance shaft shell; the corrosion resistance is good, the hardness is high, the Hardness (HBM) of the shell of the automobile double-balanced shaft reaches 82, and the tensile strength (sigma b) reaches 238 MPa; the casting yield of the automobile double-balance shaft shell product is improved from 80% to 90%, the heat treatment process is omitted, and the production cost is reduced by 5000 yuan/ton. However, in this invention, the purity of the raw material used is different from that of the present invention in that the added silicon content is 10.5%, the copper content is 2.0%, and the used raw material is 99.8%. And the casting process parameters of the corresponding alloys are different when the alloy addition amount is different; the metal mold casting method used by the invention is mainly used for casting parts with complex shapes, and the gas content and the slag content in the alloy can not be effectively controlled.
The invention discloses an aluminum-silicon-copper-magnesium wrought aluminum alloy and a preparation method thereof, which belong to the prior patent CN100439533C (the aluminum-silicon-copper-magnesium wrought aluminum alloy and the preparation method thereof), wherein the alloy contains the following components in percentage by weight: 9.0 to 12.0 percent; copper: 3.0 to 4.0 percent; magnesium: 0.3 to 0.6 percent; iron: less than 0.30 percent; zinc: less than 0.20 percent; the impurity content is less than or equal to 0.15 percent; the balance being aluminum. Melting and refining the raw materials in a reflection smelting furnace, carrying out Al-Sr intermediate alloy modification treatment on the alloy melt, carrying out semi-continuous casting to obtain a cast rod, carrying out hot extrusion and deformation on the cast rod, and carrying out forging and T6 heat treatment to obtain the Al-Si-Cu-Mg series wrought aluminum alloy. The alloy has tensile strength of over 397MPa, elongation after fracture of 6% and hardness of 136-141HB, and is mainly used for manufacturing automobile parts such as automobile and motorcycle wheels, pistons, bearings, bidirectional swash plates and the like with high requirements on strength, toughness and wear resistance. However, the invention adopts the alloy with the purity of 99.7 percent as the raw material, and the addition amount of the alloy is more, wherein the silicon content is 9 to 12 percent, the copper content is 3.0 to 4.0 percent, the addition amount of the alloy is different, and the casting process parameters are different. And the casting process parameters of the alloy are not specified in the patent.
And aluminum wiring films are widely used in the fields of semiconductor integrated circuits and flat panel displays due to low resistivity, good etchability, and low manufacturing cost. The uniform deposition of wiring films on substrates, maintaining film formation quality with uniform thickness, plays a key role in the performance of integrated circuits having a multi-layer structure of the order of micrometers. The thickness of the wiring film is inversely proportional to the sheet resistance (Rs), so that the change in the thickness of the film directly affects the change in the resistance, resulting in a change in the signal transmission rate and power consumption, which may seriously cause a short circuit between the wiring films. The grain size, orientation and tissue uniformity of the aluminum target directly influence the film forming quality, and the tissue of the target blank has a certain genetic effect on the final product tissue, so that the as-cast structure control of the blank is one of the key technologies.
Pure aluminum films suffer from aluminum spiking, Stress Migration (SM), and Electromigration (EM) problems due to the presence of aluminum-silicon solid solution, which ultimately leads to device failure. Research has found that the addition of alloying elements to aluminum can solve the above problems. The Al-Si alloy is developed by adding Si element into pure aluminum, so that aluminum peak can be eliminated, and the stress migration resistance can be improved; the Al-Cu and Al-Si-Cu alloys are developed by adding Cu element into pure aluminum, and the electromigration resistance can be improved. The invention mainly introduces a preparation method of an aluminum-silicon-copper alloy target blank.
The ternary alloy is characterized in that a third component is added into the binary alloy to form a ternary melt, the addition of the third component can change the solubility among original alloy components and even generate a new composition phase, for example, binary aluminum silicon and aluminum copper alloy can predict the casting temperature and the casting process of the alloy according to a binary alloy phase diagram, and the ternary alloy changes the solubility of the original alloy components, because the addition amount of silicon and copper alloy in the ternary alloy is less in 1% of aluminum silicon and 0.5% of copper, the silicon and copper alloy are mainly in a solid solution state in the ternary alloy, and a small amount of eutectic structure exists at a segregation grain boundary of the aluminum silicon component. The compound form in the alloy is not complicated, but the smelting and solidification temperatures of the aluminum-silicon-copper ternary alloy are obviously changed.
In view of the above, the invention provides a preparation method of a fine-grain high-purity aluminum-silicon-copper alloy target blank for sputtering.
Disclosure of Invention
The invention aims to provide a preparation method of a fine-grain high-purity aluminum-silicon-copper alloy target blank for sputtering, which controls the purity, homogenization and accurate addition of components by a self-prepared high-purity aluminum-silicon, aluminum-copper intermediate alloy and intermediate alloy fractional addition process; the control of the product components with the purity of 99.9995 percent or more is realized by controlling the materials of the furnace lining and the launder lining in the casting process; the internal structure of the bar blank is controlled to be uniform, no feather crystal defect exists, the surface quality is excellent through strict casting parameter design, and the casting molding problems of high purity, uniform structure, no feather crystal defect and the like of the high-purity AL-1 wt% Si-0.5 wt% Cu target blank for sputtering are solved.
In order to realize the purpose, the adopted technical scheme is as follows:
a preparation method of a fine-grain high-purity aluminum-silicon-copper alloy target blank for sputtering comprises the following steps:
s10 preparing a master alloy: the intermediate alloy is an aluminum-copper intermediate alloy and an aluminum-silicon intermediate alloy;
preparing an aluminum-silicon intermediate alloy: melting high-purity aluminum with the purity of 99.9995 percent and high-purity silicon with the purity of not less than 99.999 percent in a vacuum melting furnace, controlling the melting temperature at 800-850 ℃, completely melting, stirring, and casting into a re-melted ingot to obtain the aluminum-silicon intermediate alloy: the content of silicon element in the aluminum-silicon intermediate alloy is 7-13 wt%;
preparing an aluminum-copper intermediate alloy: melting high-purity aluminum with the purity of 99.9995 percent and high-purity copper with the purity of not less than 99.999 percent in a vacuum melting furnace, controlling the melting temperature at 800-850 ℃, completely melting, stirring, and casting into a re-melted ingot to obtain the aluminum-copper intermediate alloy: the content of copper element in the aluminum-copper intermediate alloy is 20-25 wt%;
s20: melting the intermediate alloy and high-purity aluminum with the purity of 99.9995 percent in a vacuum melting furnace, controlling the melting temperature to be 730-745 ℃, and obtaining alloy liquid after complete melting; the alloy liquid contains 0.9-1.1 wt% of silicon and 0.45-0.55 wt% of copper;
s30: carrying out on-line refining on the alloy liquid by adopting high-purity argon;
s40: carrying out bipolar filtration on the alloy liquid subjected to online refining;
s50: and casting the alloy liquid subjected to the two-stage filtration on a phi 120-164mm bar blank to obtain the fine-grained high-purity aluminum-silicon-copper alloy target blank for sputtering.
Furthermore, in the preparation method, the content of alumina in the lining material of the part contacting with the molten aluminum in the casting production line is required to be higher than 90 wt%.
Further, in step S10: in the preparation of the aluminum-silicon intermediate alloy: stirring the aluminum liquid for 15min by using a graphite rotor after complete melting;
in the preparation of the aluminum-copper intermediate alloy: and stirring the aluminum liquid for 15min by using a graphite rotor after complete melting.
Further, in step S10: before casting into a re-melted ingot, detecting the components of the intermediate alloy in the intermediate alloy liquid, detecting and preparing the components of the intermediate alloy of aluminum silicon and aluminum copper by using a glow discharge mass spectrometer, and controlling the total content of metal element impurities in the intermediate alloy to be less than 5 ppm.
Further, in the step S20, the intermediate alloy is added twice, where the first addition amount is 80 wt% of the total addition amount;
further, in S30, the argon flow is 2-5m3/h, the refining time is 20min, and the refining temperature is 730-.
Furthermore, in the step S40, two filter plates are adopted for online filtration; wherein the first stage filtration adopts a domestic 50PPI filter plate, and the second stage filtration adopts an imported 50PPI filter plate or a domestic 70PPI filter plate.
Further, in S50, a semi-continuous casting machine is used to perform water cooling for casting the bar blank with the diameter of phi 120-3/h。
Further, in S50, a smooth aluminum alloy mold is used for casting.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention uses a semi-continuous casting method to prepare the high-purity aluminum-silicon-copper alloy target blank for sputtering. The purity and uniformity of the alloy components are controlled by a casting process. The semi-continuous casting process has excellent degassing and deslagging effects, so that the process is suitable for industrial batch production.
2. The invention self-mixes the high-purity aluminum silicon and the high-purity aluminum silicon copper intermediate alloy and casts the intermediate alloy into the bar blank, thereby realizing the purity control of the intermediate alloy components and ensuring the uniformity of the alloy components. The technological processes of vacuum melting, on-line refining and bipolar filtration are adopted, so that the cast bar blank has uniform components, low content of trace elements and smooth surface, and has no defects of impurities, air holes, shrinkage cavities and the like. According to the invention, the temperature interval of ternary alloy casting is selected, and the semi-solid temperature interval is adopted to prepare the fine-grained structure, so that the blank is convenient to deform and process.
3. The invention controls the content of impurity elements in the high-purity aluminum-silicon-copper alloy target blank for sputtering to be at an extremely low level through the process flow design, wherein the content of alkali metal elements such as Na, K and the like is less than or equal to 0.2 ppm; fe. The content of heavy metal elements such as Ni is less than or equal to 1 ppm; u, Th and other radioactive elements are less than or equal to 0.005 ppm; C. o, N, etc. with the impurity content less than or equal to 10 ppm.
4. The high-purity Al-1 wt% Si-0.5 wt% Cu target blank for sputtering prepared by the invention has extremely low trace impurity element content and good sputtering film-forming performance.
5. The high-purity Al-1 wt% Si-0.5 wt% Cu target blank prepared by the method has uniform components, and has equiaxial crystal structure and uniform structure inside. The bar has smooth surface, no defects of inclusion, air holes, shrinkage cavities and the like, and no coarse columnar crystals and feather crystal defect tissues.
Drawings
FIG. 1 is a phase diagram of an AL-Si-Cu ternary alloy;
FIG. 2 is a process flow diagram of the preparation method of the fine-grained high-purity aluminum-silicon-copper alloy target blank for sputtering of the invention;
FIG. 3 shows an AL-1 wt% Si-0.5 wt% Cu planktonic structure;
FIG. 4 is an Al-1 wt% Si-0.5 wt% Cu equiaxed grain structure;
FIG. 5 shows the Al-1 wt% Si-0.5 wt% Cu feather grain defect structure.
Detailed Description
In order to further illustrate the preparation method of the fine-grained high-purity aluminum-silicon-copper alloy target blank for sputtering according to the present invention and achieve the intended purpose, the following detailed description is provided with reference to the preferred embodiments, and the specific implementation, structure, characteristics and effects thereof of the preparation method of the fine-grained high-purity aluminum-silicon-copper alloy target blank for sputtering according to the present invention are described in detail. In the following description, different "one embodiment" or "an embodiment" refers to not necessarily the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
The following will further describe the preparation method of the fine-grained high-purity aluminum-silicon-copper alloy target blank for sputtering in detail with reference to specific embodiments:
the technical scheme of the invention is as follows:
(1) ultra-pure raw materials: the purity of the high-purity aluminum is 99.9995 wt%, the purity of the high-purity silicon is 99.9999 wt%, and the purity of the high-purity copper is 99.999 wt%.
(2) Preparing a master alloy:
a, preparing an aluminum-silicon intermediate alloy: preparing intermediate alloy of high-purity aluminum and high-purity silicon in a vacuum smelting furnace according to the mass ratio of 7-13 wt%, and controlling the temperature of aluminum liquid at 800-. And stirring the aluminum liquid for 15min by using a graphite rotor after the aluminum liquid is completely melted, controlling the component uniformity of the aluminum liquid, and casting into a re-melted ingot.
b, preparing an aluminum-copper intermediate alloy: preparing intermediate alloy by the mass ratio of 20-25% of high-purity aluminum and high-purity copper in a vacuum smelting furnace, and controlling the temperature of aluminum liquid at 800-. And stirring the aluminum liquid for 15min by using a graphite rotor after the aluminum liquid is completely melted, controlling the component uniformity of the aluminum liquid, and casting into a re-melted ingot. The remelted ingot is added as an aluminum-silicon-copper bar alloy raw material.
Detecting the components of the master alloy: detecting and preparing components of the aluminum-silicon and aluminum-copper intermediate alloy by using a glow discharge mass spectrometer, wherein the number of detected elements is more than or equal to 70, and the total content of metal element impurities in the intermediate alloy is controlled to be less than 5 ppm.
(3) Preparing an alloy: adding the ultra-pure aluminum and the intermediate alloy into a vacuum smelting furnace, wherein the content of the added silicon is controlled to be 0.9-1.1 wt%, and the content of the copper is controlled to be 0.45-0.55 wt%. The intermediate alloy adopts a twice adding process, the adding amount of one time is 80 wt% of the total adding amount, the intermediate alloy ingot is placed at the center position in the furnace, the alloy ingot is convenient to smelt and homogenize components, and after the component detection is matched with the pre-prepared components without errors, the rest 20 wt% is added to ensure the component uniformity. The smelting temperature of the aluminum liquid is controlled to be 730-745 ℃.
The intermediate alloy adopts a twice adding process, namely the amount of the once added alloy is 80 wt% of the total amount, the intermediate alloy is completely melted and then is kept warm and kept stand for 20min, the components are controlled to be uniform through the electromagnetic stirring effect, and the secondary intermediate alloy addition is carried out after the sampling component detection. Controlling the trace impurity elements in the melt at an extremely low level: the content of alkali metal elements such as Na, K and the like is less than or equal to 0.2 ppm; fe. The content of heavy metal elements such as Ni is less than or equal to 1 ppm; u, Th and other radioactive elements are less than or equal to 0.005 ppm; C. o, N, etc., and has impurity content less than or equal to 10ppm and H content less than or equal to 0.5 ppm.
Casting production line lining material model selection: the purities of the raw materials of aluminum, silicon and copper used for casting are all higher than 99.999 wt%, so that the content of alumina in the lining material contacting with molten aluminum in a casting production line is higher than 90 wt%.
(4) And (3) online refining: adopting high-purity argon for on-line refining, wherein the flow of the argon is 2-5m3And/min, refining for 20min, and standing for 30min after refining is finished.
(5) Bipolar filtration, in-line filtration using two 50PPI porosity filter plates. Wherein the first stage filtration adopts a domestic 50PPI filter plate, and the second stage filtration adopts an imported 50PPI filter plate. (import 50PPI filter approximately equal to domestic 70PPI filter capacity)
(6) Casting a bar blank: adopting a low-temperature (semi-solid melt) casting process technology, performing water cooling on the bar blank with the diameter of 120 plus 164mm by using a semi-continuous casting machine, controlling the temperature of aluminum liquid in the crystallizer to 655 plus 665 ℃, the casting speed to 100 plus 120mm/min and the cooling water flow to 15-20m3H is used as the reference value. And a smooth aluminum alloy crystallizer mould (a special aluminum alloy metal crystallizer is adopted, the floating crystal defect structure caused by aluminum liquid nucleation in the traditional hot cap crystallizer is changed, and the equiaxed crystal fine-grained structure is obtained).
The Al-Si-Cu ternary alloy phase diagram is shown in figure 1, and according to the ternary alloy phase diagram, the melting point of Al-1 wt% Si-0.5 wt% Cu alloy is 610-620 ℃. The conventional casting temperature is 50-70 ℃ higher than the melting point, while the casting temperature is selected to be 30-50 ℃ higher than the melting point, and a semi-solid casting temperature interval is taken. As 0.9-1.1 wt% of Si element and 0.45-0.55 wt% of Cu element are added in the ternary alloy, the ternary alloy is mainly in a solid solution state, the melt is free from heterogeneous nucleation points, more nucleation points exist in the aluminum liquid before the aluminum liquid enters the crystallizer during semisolid low-temperature casting, the uniform equiaxial crystal structure is obtained by instant crystallization after the aluminum liquid enters the crystallizer and is cooled, the formation of coarse columnar crystal structures and the formation of feather crystal forms are avoided, and the casting temperature range is determined to be 655-plus 665 ℃.
In the technical scheme of the invention, a special aluminum alloy metal crystallization die is adopted for casting, and is used for preventing floating crystal from forming. The conventional bar casting crystallizer is a hot-top graphite ring crystallizer. As the semi-solid casting temperature is adopted in the scheme, the aluminum liquid is easy to nucleate and grow on the inner wall of the hot-top crystallizer, and drops into the bar in the casting process to form a coarse floating crystal structure as shown in figure 3. In order to avoid nucleation of the suspended crystal defect tissue inside the bar, the scheme adopts a specially-made aluminum alloy metal crystallization mold, and the smooth aluminum alloy crystallizer can prevent nucleation of crystal grains on the inner wall of the crystallizer, so that formation of thick suspended crystal tissue is avoided, and finally refined and uniform equiaxed crystal tissue is obtained.
The invention prepares the high-purity aluminum-silicon-aluminum-copper intermediate alloy by vacuum melting with a high-purity aluminum raw material with a purity of more than 99.9995 wt%, high-purity copper with a purity of 99.999 wt% and high-purity silicon with a purity of more than 99.9999 wt%. The vacuum melting furnace is used for controlling the uniformity of alloy components by adopting an intermediate alloy twice-adding process and matching with an electromagnetic stirring effect, and a low-temperature (semi-solid melt) casting process is used for preparing a high-purity fine-grain AL-1 wt% Si-0.5 wt% Cu alloy target blank, so that coarse columnar grains and feather grain defect tissues are inhibited, and the requirement of uniform and fine-grain internal tissues of a sputtering target is met.